1. Technical Field
The present invention is directed to network computing. More specifically, the present invention is directed to a method, system and apparatus for relating time set on one computer system to time set on another computer system on a network.
2. Description of Related Art
Most computer systems have a real-time clock. Real-time clocks are clocks that run on a battery and thus, are able to keep track of time even when the computer systems are turned off or disconnected. As with regular clocks, real-time clocks may be fast, slow, set ahead or behind local time etc.
Real-time clocks are used to indicate current date and time of day. In addition, the clocks are used to timestamp files. To timestamp a file is to indicate in the file the date and time the file was created. This allows users to determine which files are the most recent in a group of files. This feature can be rather important, especially, in this day and age of network programming.
Network programming allows programmers located anywhere in the world to collaborate in writing a software program. The programmers may be working on different files or on the same files. The files can then be compiled and linked to each other to be converted into the software program.
Recently, different tools have been made available to facilitate network programming. One of these tools is the network file system (NFS). NFS is a client-server application that allows network users to access shared files stored on computer systems of different types. Users can manipulate shared files as if they were stored locally (i.e., on the users' own hard disk). With NFS, computer systems connected to a network operate as clients when accessing remote files and as servers when providing remote users access to local shared files. The NFS standards are publicly available and widely used.
Thus, a user may work on remote files as well as local files. But, when a file is created remotely, the real-time clock running on the remote computer system is used to timestamp the file. Likewise, if a file is created locally, the real-time clock of the local computer system is used to timestamp the file. Thus, as mentioned above, being able to relate different real-time clocks to each other in order to determine which files are the most recent becomes quite necessary.
Furthermore, some compilers are designed to automatically compile files. These compilers use file timestamps to determine which files to compile. As an illustration, suppose a program is written in the C language, the program will have “.C” extension. If the program is compiled, there will be a corresponding object file with “.O” extension. If the program is supposed to work with other files or use library files etc., all the files will have to be linked to each other in order to form an “.EXE” file. Note that in DOS or WINDOWS operating systems, the executable file has an “.EXE” extension. However, in UNIX, the executable file does not have an extension.
In any event, all the files (i.e., “.C”, “.O” “,EXE” etc.) will have a timestamp. If a user modifies the “.C” file, the file will have to be recompiled. Presently, some compilers compare timestamps of “.O” files to those of corresponding “.C” files to determine whether the “.C” files need to be compiled. If a “.C” file has a timestamp that is more recent than a corresponding “.O” file, then the “.C” file must have been created after the “.O” file and thus, has not yet been compiled. Hence, the compiler will automatically compile the “.C” file.
When the “.O” and the “.C” files are on different computer systems and the real-time clock of the computer system on which the “.C” file resides is slower, on a different time zone (i.e., time zone behind that of the other computer system) or for some reason is set behind the other computer system's real-time clock, the compiler may not determine that the “.C” file has not been compiled yet.
Therefore, there is a need for an apparatus, system and method of relating one real-time clock to another to determine which files are the most recent files.